In several technical fields where components are coupled together that do not have a standardized interface, there exists a desire for connection elements that are tolerant regarding the dimensional design of the components. One of these fields is the extraction of liquid drugs from drug reservoirs (e.g. vials or cartridges, in the medical field), where depending on the supplier or the size of the drug reservoir, different geometric shapes of the physical interfaces may have to be covered, often resulting in a desire to provide a separate adapter for each variety.
In particular, in the therapy of diabetes with the use of an insulin pump, the insulin ampoules used in the insulin pump often are not purchased as readily filled products but as empty ampoules which are then, with the aid of a filling device, filled prior to use with insulin from a vial or a pen-cartridge containing the specific type of insulin preferred by the patient. However, while the 10 ml vials typically have a cap diameter of about 14 mm, the 3 ml pen-cartridges may have a cap diameter of about 7 mm, which is a range that could not be handled by many current connecting element designs, thus resulting in the requirement of different filling device adapters for the individual reservoir types.